1. Field of the Invention
The present invention relates to a magnetic tape recording/reproducing format and apparatus in accordance therewith, and more particularly, to an HDTV recording/reproducing magnetic tape format and apparatus which has backward compatibility to another format, such as the standard VHS television signal recording format.
2. Description of the Prior Art
U.S. Pat. No. 4,963,991 issued to Honjo on Oct. 16, 1990 discloses a tape recording format and recorder apparatus which allows recording/reproduction of television signals in both a narrow bandwidth format, such as a conventional NTSC signal having a bandwidth of approximately 4 mHz, and a wide bandwidth format, such as a high definition television signal (HDTV) having a bandwidth of 8-20 mHz. This is accomplished by recording only one of the narrow bandwidth or wide bandwidth signals on the tape at a time. When wide bandwidth signals are recorded, instead of increasing the speed of the recording tape, two smaller heads are used for digitally recording time-expanded channels of the wide bandwidth signal, and the speed of the rotating drum in which the recording heads are mounted is correspondingly increased. Thus, tape speed is the same for both formats. However, since only one format at a time is recorded on the tape, video tape players not equipped to play the television signal which was selected for recording on the tape will not be able to use these tapes.
U.S. Pat. No. 4,941,055 issued on Jul. 10, 1990 to Fujimoto discloses a format for magnetic recording on a video floppy disk a wide band video signal which is divided into two signals; one, a low frequency component in the frequency range below 4 mHz, and the other in the high frequency range, 4-6 mHz. The low frequency component is recorded in a plurality of main slant tracks having spaces therebetween, and the high frequency component is recorded in the guard band between the main tracks and at an azimuth angle which is different from the main track in order to minimize pick-up of the adjacent track during head mistracking. (The azimuth angles of heads on headwheels used for helically scanning of magnetic tape are customarily measured with repect to a line perpendicular to the plane of headwheel rotation, and the azimuth angles of recorded tracks refer back to the heads used in recording them in a magnetic tape surface; these customs are followed in this specification and its accompanying drawing.) Although two track recording is disclosed, only one television signal format is recorded/reproduced. Thus, there is no simultaneous compatibility with another television signal recording format, which would increase the desirability and user demand for such tapes when pre-recorded with multiple television signal formats. Furthermore, since the total frequency content of a single signal is split among two channels and two recording/pick-up heads, it is the belief of the present inventors that time-base errors will necessarily exist between the reproduced signals which will be impossible to correct with even the best time base correctors, thereby resulting in unacceptable HDTV performance.
U.S. Pat. No. 4,843,485 issued to Reitmeier on Jun. 27, 1989 discloses a recording format and recording/reproducing apparatus in accordance therewith which simultaneously provides for recording/reproducing one of either a wide bandwidth (studio quality) signal or a narrow bandwidth (portable quality) television signal on a magnetic tape. Here, the tape is longitudinally divided into upper and lower halves. Each half receives digital recording of one half of the signal components of the wide bandwidth signal, so that pick-up of only one longitudinal track results in reproduction of a low quality signal, while pick-up of both tracks simultaneously results in a high quality signal.
U.S. Pat. No. 4,928,186 issued to Matsamoto et al. on May 22, 1990 discloses a tape recording format and recording/reproducing apparatus in accordance therewith which records a video signal on the main tracks of a video floppy disk, and also records additional information (audio) in the guard band space which exists between the main tracks. An additional aspect of this patent is that the guard band signal should be recorded with an electromotive force which is only 40-80% of the electromotive force used in the main tracks, in order to minimize deterioration of the main tracks during recording of the guard band tracks.
It is an object of the present invention to provide a magnetic media recording format which allows recording of two different signals in two different formats on one media, and selective reproduction of signals from either one of the two recorded formats.
It is a further object of the invention to provide a recording format in which it is relatively simple to record and then reproduce signals therefrom.
These and other objects of the invention will become apparent from the following detailed description of a preferred embodiment of the invention, the accompanying drawings and the claims.